TS series transformers for supplying extra-low voltage (SELV), suitable for loads that require short-term supply, particularly doorbells and chimes. In addition to perfect insulation and separation between the primary and secondary circuits, TS transformers have a thermal protection device integrated in the secondary part, making them resistant to short-circuit currents (conditionally short-circuit-proof). They are equipped with a thermal protection device that automatically restores operation when the transformer has cooled down sufficiently or the overload has been eliminated. The ...ES series bell transformers are characterized by 50% reduced energy consumption in idle mode.